SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b268aac576e6f6308a8e066e9f3a728c1fdcbd43d5a7c6344045d8228c3280fc' 
  AND token = 'xdivw87Cus/Bug9HDfiqYo8n1/ztxUQGVvQqVUU1YOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}